Actually the cardinal rule of marketing is to get attention. Angry customers are far more beneficial to a company than apathetic ones, and you don't really have to market for happy fans since you've already got them. Angry fans are likely to purchase your products to see if their anger is justified, or continues to be justified, whereas an apathetic one isn't.
The cardinal rule of marketing after all is growing your most profitable customers,
Getting attention the wrong way is not beneficial to a company. Apathetic customers who pay for you product are better than angry customers, but happy cutomers are even better. I really do not agree that angry customers are likely to purchase products to justify their angry. Mine certainly are not.
The cardinal rule I cited is well established in marketing theory (a la Phillip Kotler, one of the leading minds in marketing). I have no idea where you got yours.